An important aim of ongoing research in the semiconductor industry is increasing semiconductor performance while decreasing power consumption in semiconductor devices. Planar transistors, such as metal oxide semiconductor field effect transistors (MOSFET) are particularly well suited for use in high-density integrated circuits. As the size of MOSFET and other devices decrease, the dimensions of source/drain regions, channel regions, and the gate electrodes of the devices, also decrease.
As the channel length decreases, short-channel effects increase. Short-channel effects include punchthrough and decreased threshold voltage at the gate edge in the off state (VT).
Halo implants eliminate short-channel effects by increasing VT at the gate edge and repeats eliminating punchthrough. Halo implants (also called pocket implants) are ring-shaped implants formed in the channel region, adjacent the source/drain regions. Halo implant regions are formed with a conductivity type opposite that of the source/drain regions. Halo implant regions prevent merger of the source/drain regions in the channel region. The halo implant regions provide an abrupt transition between the source/drain extensions and the channel region. Typically, halo implant regions have a lower concentration of dopant than the source/drain extensions.
One shortcoming of conventional halo implants is the difficulty in precisely controlling the location and boundaries of the halo implant region. As devices become smaller and channel lengths decrease, the location and the boundaries of the halo implant regions becomes more critical.
The term semiconductor devices, as used herein, is not to be limited to the specifically disclosed embodiments. Semiconductor devices, as used herein, include a wide variety of electronic devices including flip chips, flip chip/package assemblies, transistors, capacitors, microprocessors, random access memories, etc. In general, semiconductor devices refer to any electrical device comprising semiconductors.